Pulse generator



Jan. 24, 195 R. D. HANCOCK PULSE GENERATOR Filed Dec. 5, 1950 1 5M 1 4 MA I W 3w 1 4 ,x 2/ 3 654 106627' 0. #A/VCOCK.

///s Avravr lrramvar United States Patent PULSE GENERATOR Robert D.Hancock, Compton, Calif., assignor t o Northrop Aircraft, Inc.,Hawthorne, Calif., a corporation of California Application December 5,1950, Serial No. 199,172

7 Claims. (Cl. 250-36) The present invention relates to pulse generatorsand more particularly to a pulse generator capable of emitting aspecified number of pulses upon being energized.

It is an object of the invention to provide a simple glow tube pulsegenerator emitting a specified number of output pulses whenever thecircuit is energized.

Briefly, the present invention includes a glow discharge tube having ananode and a plurality of cathodes therein immersed in an ionizable gasat glow discharge pressure. A source of positive potential is connectedto the anode through a limiting resistor, and a time constant circuit isconnected to each cathode, and to the negative end of the source. Eachtime constant circuit is designed to have a different time constant.

A switch is provided in the source circuit which, when closed, willcause the tube to strike. Because of the different RC combinations, thecathode connected to the circuit having the shortest time constant willstrike first, followed by the striking of additional cathodes in orderof the time constants of their connected circuits. By means of an outputcircuit connected to the anode, the voltage drops across the limitingresistor, as each of the cathodes strike, are differentiated as outputpulses. Thus, a train of pulses is generated equal in number to thenumber of cathodes, and spaced in time according to the time constantsof the connected circuits.

The invention will be more fully understood by reference to the figurewhich shows one preferred circuit embodying the present invention.

In the figure, an envelope 1 containing an ionizable gas at glowdischarge pressure, such as for example, helium at 200 mm. mercurypressure, also contains an anode 2 and a plurality (five in thisinstance), of cathodes 3, 4, 5,

6 and 7. The cathodes 3, 4, 5, 6 and 7 are respectively connected to oneend of cathode resistances 3r, 4r, 5r, 6r and 7r, the other ends ofwhich are connected together and to the negative end of a potentialsource 10 through a switch 8. The positive end of source 10 is connectedto anode 2 through an anode line 11 connected to anode 2 through ananode resistance 12.

Cathodes 3, 4, 5, 6 and 7 are connected to anode line 11 through cathodecapacities 3c, 40, 5c, 60 and 70 respectively, thereby forming a timeconstant circuit connected to each cathode. The values of theresistances and the capacities are chosen such that the time constant isprogressively larger for each cathode. A suitable series of timeintervals, given only by way of an example, is as follows:

Cathodes 3 RC=1 time unit Cathode 4 RC=2 time units Cathode 5 RC=4 timeunits Cathode 6 RC=8 time units Cathode 7 RC=16 time units An ouput line15 containing an output condenser 16 is connected to anode 2.

In operation, switch 8 is closed, and current from source 10 will chargecapacity 30 sufficiently that a glow dis- 2,732,497 Patented Jan. 24,1956 charge will be struck between cathode 3 and anode 2 before anyother of the capacities 40, 5c, 60 and 7c are charged sulficiently tocause a glow to be struck on their connected cathodes. However, as timepasses, each of the other capacities will in turn be charged and a glowwill be established between the particular cathode and anode 2, untilall of the cathodes have had the glow discharge struck thereon.

As each glow discharge is struck, a drop in voltage at the anode 2 willbe realized due to additional current flowing through anode resistor 12.The resistor 12 and output line capacity 16 combination differentiatesthese voltage drops, causing a pulse on the output side of capacity 16as each cathode is struck. The number of pulses appearing in the outputwill, therefore, be equal to the number of cathodes in the tube, and thepulse spacing will be in accordance with the relative time constants ofthe cathode connected circuits. Thus, while I have shown and described atube having only five cathodes, any number desired can be used, with anydesired time spacing of the output pulses. It is also to be noted thatswitch 8 can be any type of switch, such as for example, an electronicgate.

From the above description it will be apparent that there is thusprovided a device of the character described possessing the particularfeatures of advantage before,

While in order to comply with the statute, the invention has beendescribed in language more or less specific.

as to structural features, it is to be understood that the invention isnot limited to the specific features shown, but that the means andconstruction herein disclosed com prise a preferred form of putting theinvention into effect, and the invention is, therefore, claimed in anyof its forms or modifications within the legitimate and valid scope ofthe appended claims.

What is claimed is:

I. A pulse generator comprising a tube having an envelope containing ananode and a plurality of cold cathodes immersed in an ionizable gas atglow discharge pressure, a separate and different time constant circuitconnectable between each of said cathodes and said anode through apotential source suflicient to strike all of said cathodes, means forconnecting all of said time constant circuits simultaneously to saidsource to strike said cathodes in the order of the time constants of thecircuits connected thereto, and means for differentiating resultantchanges in current flow to said anode as output pulses.

2. A pulse generator in accordance with claim 1 wherein said timeconstant circuits are arranged to have time constants causing saidcathodes to strike in a related series of time intervals.

3. A pulse generator comprising a tube having an envelope containing ananode and a plurality of cold cathodes immersed in an ionizable gas atglow discharge pressure, a separate and different time constant circuitconnectable between each of said cathodes and said anode through apotential source sufiicient to strike all of said cathodes and through aseries anode resistor, an output circuit including a capacity connectedto said anode, and means for connecting all of said time constantcircuits simultaneously to said source to strike said cathodes in theorder of the time constants of the circuits connected thereto.

4. In a pulse generator for producing a specified number of electricalpulses upon being energized, a tube having an envelope containing ananode and a plurality of cold cathodes immersed in an ionizable gas atglow dis- .9 charge pressure, a single load resistance connected at oneend to said anode, a source of potential connected at one end to theother end of said load resistance, a plurality of cathode resistances,one thereof connected to each of said cathodes, a plurality ofcapacities, one thereof being connected between each of said cathodesand said other end of said load resistance, and means for simultaneouslyconnecting all of said cathode resistances to said anode through saidsource and said load resistance in series, thereby creating a timeconstant circuit connected be tween each cathode and said anode, theresistance ca,- pacity combination of each cathode connected circuitbeing different to provide different time constants thereof, wherebysaid cathodes are struck in the order of the time constants of theconnected circuits, and whereby the incremental changes in voltageacross said load resistance as said cathodes are struck provide a basisfor output indications in accordance with the time of striking.

5. A pulse generator comprising a tube having an envelope containing ananode and a plurality of cold cathodes immersed in an ionizable gas atglow discharge pressure, a source of potential connected at one end tosaid anode, a plurality of resistances, one thereof connected to each ofsaid cathodes, a plurality of capacities, one thereof being connectedbetween each of said cathodes and said anode, and means forsimultaneously connecting all of said resistances to said anode throughsaid source, thereby creating a time constant circuit connected betweeneach cathode and said anode, the resistancecapacity combination of eachcathode connected circuit being different to provide different timeconstants thereof, whereby said cathodes are struck in the order of thetime constants of the connected circuits and means for differentiatingresultant changes in anode current as output pulses.

6. A pulse generator comprising a tube having an envelope containing ananode and a plurality of cold cathodes immersed in an ionizable gas atglow discharge pressure, a source of potential connected at one end tosaid anode, a plurality of resistances, one thereof connected to each ofsaid cathodes, a plurality of capacities, one thereof being connectedbetween each of said cat11- odes and said anode, means forsimultaneously connectsource, thereby creating a time constant circuitconnected between each cathode and said anode, the resistancecapacitycombination of each cathode connected circuit being different to providedifferent time constants thereof, whereby said cathodes are struck inthe order of the time constants of the connected circuits, an anoderesistance in series with said anode and said time constant circuits,and a capacitative output line connected to said anode.

7. A pulse generator for producing a specified number of electricalpulses, comprising a glow-discharge tube having an envelope containing asingle anode and a plurality of cathodes all in operating relationshipwith said anode and immersed in an ionizable gas at glow dischargepressure. a limiting resistance connected at one end to said anode, asource of direct current potential connected at one end to the other endof said limiting resistance, a plurality of separate additionalresistances, one thereof connected to each of said cathodes, a pluralityof capacitances, one thereof connected between each of said cathodes andsaid other end of said limiting resistance, means for simultaneouslyconnecting all of said additional rcsistances to the other end of saiddirect current potential source, thereby creating a time constantcircuit connected between each cathode and said anode, theresistancecapacity combination of each said time constant circuit beingdifferent to provide different time constants thereof, and means fordifferentiating resultant abrupt changes in voltage across said limitingresistance into output pulses, as striking of each cathode occurs,whereby the number and spacing of said output pulses after saidconnecting means closes said circuits is governed by the number andvalue of said time constant circuits.

References Cited in the file of this patent UNITED STATES PATENTS1,832,402 Langer Nov. 17, 1931 2,524,213 Wales, Ir. Oct. 3, 19502,553,263 Loughren May 15, 1951 2,553,585 Hough May 22, 1951 2,575,517Hagen Nov. 20, 1951

